GB2589928A

GB2589928A - Filter assembly & pumping system

Info

Publication number: GB2589928A
Application number: GB1918425.8A
Authority: GB
Inventors: Peter Hosford James
Original assignee: Individual
Current assignee: Individual
Priority date: 2019-12-13
Filing date: 2019-12-13
Publication date: 2021-06-16
Also published as: GB201918425D0

Abstract

A filter assembly (3) for filtering liquids contaminated with solid material. The filter assembly (3) includes: a tubular filter (7); and a cleaning system (9) for cleaning the tubular filter (7). The cleaning system (9) includes a rotor (11) mounted within the tubular filter (7), the rotor (11) having a first helical formation (13). The first helical formation (13) includes a conduit (17) and a at least one first outlet (21) in fluid communication with the conduit. In use, the conduit is arranged to provide liquid to the at least one first outlet, and the at least one first outlet is arranged to direct jets of liquid on to an internal surface of the tubular filter. The filter assembly provides for dislodging solid contaminates from a filter and causes contaminates located outside a tubular filter to flow axially towards a solids collection zone. Additionally solids backwashed from the filter mesh are moved off the filter screen quickly by the cleaning system which prevents solids build up.

Description

FILTER ASSEMBLY & PUMPING SYSTEM The invention relates to a filter assembly for filtering liquids contaminated with solid materials, for example dirty water, and a filtration system that includes the filter assembly. The invention is particularly, though not exclusively, suited for in-line 5 systems.

Self-cleaning filter systems for fluids are well known. A common type is one that is incorporated into a pipeline or conduit, where the fluid contaminated with suspended solid particles enters a vessel that contains a filter element. This is commonly referred to as an "in-line system". The fluid passing through a mesh filter and the filtered fluid exits the vessel through a further conduit. The solid particles that are too large to pass through the filter mesh are retained in a vessel where they are removed periodically via a valve.

Several different designs of mechanism have been developed to keep the filter mesh from blocking during use. These range from suction scanners to scrapers that work on the dirty side of the filter mesh. The disadvantages of self-cleaning mechanisms working on the contaminated fluid side of the filter mesh is that larger debris in the fluid can become entangled and snag the mechanism.

Further disadvantages of scraper systems are that they tend to force the particles into the pores of the filter mesh. They also wear the scrapers and the filter mesh 20 leading to high maintenance costs.

Suction scanner type systems suck the debris that has accumulated on the filter mesh and exhaust it to the atmosphere. Typically, these are activated when the solid matter has built up on the mesh. In heavily contaminated fluids this can happen very quickly, and the scanner is activated very frequently with a lot of fluid exhausted with the solids. There are several other systems, but most of them rely on the filter element blocking and then a cleaning cycle starts.

It is often important to the end user that the self-cleaning filter system has at least one of the following characteristics: it is as compact as possible for a given capacity; it is able to filter fluids heavily contaminated with solids; it has a low fluid loss when exhausting filtered solids; and has a low requirement for maintenance and replacement parts.

Accordingly, the invention seeks to mitigate at least one of the above-mentioned problems or at least to provide an alternative filter assembly and pumping system 10 to known assemblies and systems.

According to one aspect there is provided a filter assembly according to claim 1. Liquid, such as water, contaminated with solids flows from outside the tubular filter to inside the tubular filter, with the tubular filter removing at least some of the solid contaminates from the liquid as the liquid pass through the filter. Liquid on the outside of the filter is contaminated liquid. Liquid on the inside of the filter is cleaned liquid. During the filtering process, typically some of the solid contaminants become lodged on the filter. The cleaning system dislodges the solid contaminates attached to the tubular filter by directing jets of liquid on to the filter as the rotor rotates, thereby cleaning the filter. The helical arrangement of the rotor locates the outlets in close proximity to an internal surface of the tubular filter so that the jets of liquid have maximum effect to dislodge solid contaminates. The first helical formation also causes contaminates located outside of the tubular filter to flow axially towards a solids collection zone, for example a vessel sump. This occurs because rotation of the first helical formation has the effect of moving liquid outside of the tubular filter in a generally axially direction. Furthermore, solids backwashed from the filter mesh are moved off the filter screen quickly by the cleaning system which prevents solids from building up in a cloud around the tubular filter. If this did not happen, the concentration of solids may build up over time, which can reduce the ability of the cleaning system to stop the tubular filter from blocking.

According to another aspect a filter assembly for filtering liquids contaminated with solid material.

The filter assembly can include a tubular filter.

The filter assembly can include a cleaning system. The cleaning system can be arranged to clean the tubular filter. The cleaning system can include a rotor. The rotor can be mounted within the tubular filter. The rotor can include a first helical formation. The first helical formation can include a first conduit. The first helical formation can include at least one first outlet. The at least one first outlet can be in fluid communication with the first conduit. The conduit can be arranged to provide liquid to the at least one first outlet. The at least one first outlet can be arranged to direct jets of liquid on to an internal surface of the tubular filter.

In some embodiments there is a gap between the rotor and the internal surface of the tubular filter. The gap ensures there is no frictional engagement between the tubular filter and the rotor, which prevents the rotor wearing the filter and increases the life of the filter.

The first helical formation can include a plurality of outlets. Each outlet can comprise an aperture formed through the first helical formation to the first conduit. For example, each aperture can comprise a slot. The slot can have a width of aroundl mm. The at least one first outlet can be formed in a peripheral portion of the helical formation. For example, the at least one first outlet can be formed in a helical edge or a helical surface, and preferably in the helical edge or helical surface that is located closest to the inner surface of the tubular filter. The at least one outlet can be oriented towards the internal surface of the tubular filter. The at least one outlet can direct a jet of liquid in a radially outwards direction from the helical formation towards the inner surface of the tubular filter.

The first conduit can be an internal conduit.

The axial length of the first helical formation can be approximately equal to the axial length of the tubular filter.

The rotor can include a second helical formation. Having a double-helix type arrangement can be useful since a double helix arrangement is naturally balanced for rotation. The second helical formation can be intertwined with the first helical formation. The second helical formation can be rotationally offset from the first helical formation. For example, the second helical formation can be rotationally offset from the first helical formation by 180 degrees. The second helical formation can be similar to the first helical formation. The second helical formation can have the same rotational direction (same handed) as the first helical formation. The second helical formation can be connected to the first helical formation so that the helical formations support one another. For example, the second helical formation can be connected to the first helical formation at a first end. The second helical formation can be connected to the first helical formation at a second end. The second helical formation can be connected to the first helical formation at at least one location intermediate to the first and second ends. The rotor can include a central core that connects the first and second helical formations together along their lengths.

The axial length of the second helical formation can be approximately equal to the axial length of the first helical formation. The axial length of the second helical 23 formation can be approximately equal to the axial length of the tubular filter.

The second helical formation can include a second conduit. The second conduit can be an internal conduit. The second helical formation can include a at least one second outlet. The second conduit can be arranged to provide liquid to the at least one second outlet. The at least one second outlet can include a plurality of outlets.

The or each outlet can comprise an aperture formed through the second helical formation to the second conduit. For example, each aperture can comprise a slot. The slot can have a width of around 1mm. The at least one second outlet can be formed in a peripheral portion of the helical formation. For example, the at least one second outlet can be formed in a helical edge or a helical surface, and preferably in the helical edge or helical surface that is located closest to the inner surface of the tubular filter. The at least one second outlet can be oriented towards the internal surface of the tubular filter. The or each outlet can direct a jet of liquid in a radially outwards direction from the helical formation on to the inner surface of the tubular filter.

In some embodiments the pitch for each helical formation is approximately equal to the axial length of the tubular filter.

In some embodiments the outlet can be formed in a body which is inserted into an aperture in the helical formation. The body is preferably resilient. The body can be made from rubber or a rubber-like substance. In some embodiments, each body includes a single outlet. In some embodiments each body includes a plurality of outlets.

The rotor assembly can include at least one further helical formation. The further helical formation can be rotationally offset from the first helical formation and the second helical formation. The further helical formation can include a further conduit.

The further conduit can be an internal conduit. The further helical formation can include at least one further outlet in fluid communication with the further conduit.

In some embodiments the or each helical formation can be manufactured in one piece, for example by 3D printing or investment casting. In other embodiments, each helical formation can comprise a plurality of pieces.

The filter assembly can include drive means. The drive means can be arranged to 5 rotate the rotor.

The drive means can include a motor.

The drive means can include a pump. The pump can be arranged to rotate the rotor.

The pump can include an impeller. The pump can include a pump volute. The pump volute can be connected to the rotor. The impeller can be connected to the motor. 10 Operation of the motor can cause the impeller to rotate Liquid within pump can cause the pump volute, and hence the rotor, to rotate.

In some embodiments the motor can be connected to the impeller by a drive shaft. The drive shaft can be supported by bearings, for example lubricated ceramic bearings. Seals can be provided along the drive shaft to prevent liquid from leaking 15 out of the filter assembly.

Thus, in some embodiments, the motor rotates the rotor via a fluid coupling, there being a fluid coupling between the impeller and the pump volute. Rotation of the impeller effectively drags the pump volute into rotation. Since the rotor is connected to the pump volute, rotation of the pump volute causes the rotor to rotate. The fluid coupling can act as a reduction (step down) gearing since the rotational speed of the motor can be much higher than the rotational speed of the pump volute and rotor.

The tubular filter can have a longitudinal axis. In some embodiments the longitudinal axis of the rotor is arranged vertically. The pump volute can be connected to a first end of the rotor. For embodiments wherein the longitudinal axis of the tubular filter is oriented vertically, the first end of the rotor can be a lower end of the rotor. A longitudinal axis of the rotor can be arranged co-axially with a longitudinal axis of the tubular filter. A longitudinal axis of drive shaft can be arranged co-axially with a longitudinal axis of the tubular filter.

The pump can be arranged to supply liquid to the conduit of the first helical formation. Thus, in some embodiments, the conduit of the first helical formation can be in fluid communication with a pump outlet. For embodiments having a second helical formation, the pump can be arranged to supply liquid to the second conduit.

The second conduit can be in fluid communication with the pump outlet. The pump can be arranged to supply liquid to a conduit of the at least one further helical formation. The conduit of the at least one further helical formation can be in fluid communication with the pump outlet. The liquid supplied to the or each conduit by the pump is used to clean the tubular filter.

The pump volute can be mounted on bearings. The pump volute can be arranged to rotate relative to the tubular filter. The pump volute can be arranged to rotate relative to the impeller. The pump volute can be locked for rotation with the rotor.

The tubular filter can include a mesh. The mesh can include metal. For example, the filter can comprise a stainless steel tubular mesh. In some embodiments, the tubular filter can include a plurality of mesh layers. For example, the filter can comprise first and second mesh layers. The first mesh layer can have a first mesh grade. The second mesh can have a second mesh grade. The second mesh grade can be different from the first mesh grade. In some embodiments the first layer has a relatively fine mesh grade, for example of around 50-350 microns. In some embodiments the second mesh grade is coarser than the first mesh grade. The second mesh layer can provide a backing layer for the first mesh layer.

The tubular mesh can comprise a polymer mesh. For example, the tubular filter can comprise a nylon mesh, and preferably a monofilament nylon mesh. The tubular filter can comprise a polyester mesh. Other suitable polymers can be used.

The tubular filter can comprise a mesh having apertures that are less than or equal 5 to 0.5mm in diameter or width. In some embodiments, the mesh can have apertures that are greater than or equal to 0.5mm in diameter or width. In some embodiments, the mesh can have apertures that are less than or equal to 5mm in diameter or width.

The filter mesh can include a multiplicity of apertures. In some embodiments the widths of the outlets formed in the helical formation(s) are at least three times the 10 size of the mesh apertures. This helps to ensure that any solids passing through the tubular filter do not block the rotor outlets.

The tubular filter can have a first end. The first end can be a lower end.

The tubular filter can have a second end. The second end can be an upper end. The second end can include an end plate.

The rotor can have a second end. The second end can be an upper end. The second end of the rotor can be rotatably supported by the second end of the tubular filter. For example, one of the second end of the rotor and the end plate can include a bearing and the other of the end plate and second end of the rotor can include a shaft, which can be rotatably supported by the bearing.

In some embodiments the length of the tubular filter is greater than the diameter of tubular filter. This helps to achieve a compact design and to minimise the cost of fabricating a vessel used to housing the tubular filter.

In some embodiments at least one of the first outlets is formed in a first resilient body. The first resilient body can be inserted into a first aperture formed in the first helical formation. The first helical formation can include a plurality of first resilient bodies. The first helical formation can include a plurality of first apertures. Each first aperture can be arranged to receive a respective first resilient body. In some embodiments at least one of the second outlets is formed in a second resilient body.

The second resilient body can be inserted into a second aperture formed in the second helical formation. The second helical formation can include a plurality of second resilient bodies. The second helical formation can include a plurality of second apertures. Each second aperture can be arranged to receive a respective second resilient body.

According to another aspect there is provided a filtration system according to claim 16.

According to another aspect there is provided a filtration system.

The filtration system can include a filter assembly according to any configuration described herein.

The filtration system can include a vessel arranged to house at least part of the filter assembly. The vessel can be arranged to house at least the tubular filter and the rotor. This provides a so called "in-line" filtration system. Other filter assembly components, such as the motor, can be located outside of the vessel. The vessel can be elongate. The vessel can be tubular. The vessel can have a circular cross-section, for example to provide a cylindrical tubular structure. A longitudinal axis of the vessel can be arranged co-axially with the longitudinal axis of the tubular filter. The longitudinal axis of the vessel can be arranged vertically.

The vessel can include an ingress. The ingress can have an opening facing in an axial direction. The ingress can be arranged to supply contaminated liquid into the 23 interior of the vessel, such that contaminated liquid flows initially in a generally longitudinal direction. The contaminated liquid is received from a source, and may be delivered to the vessel from the source, for example by means of a pump and/or gravity.

In some embodiments the ingress opening faces in an axial direction away from the 5 filter assembly. For example, the opening can face in a generally upwards direction. The arrangement can be such that contaminated liquid entering the vessel is initially directed in an axial direction away from the filter assembly.

The ingress can comprise an inlet pipe. The inlet pipe can enter the vessel through a side wall of the vessel. The inlet pipe can include a bend to redirect the flow of liquid from a radial direction of the vessel to an axial direction of the vessel. In some embodiments the inlet pipe redirects the flow of contaminated liquid through 90 degrees.

In embodiments wherein the vessel is oriented vertically, the inlet pipe opening can be located above the filter assembly. For example, the inlet pipe can be located in an upper portion of the vessel. The filter assembly can be located in a mid and/or lower portion of the vessel. The vessel can include a sump at a lower portion of the vessel for collecting solids.

In embodiments wherein the vessel is oriented vertically, the inlet pipe opening preferably faces upwards so that contaminated liquid flows in an upward direction 20 initially.

The vessel can include an endcap. In use, the ingress can direct the flow of contaminated liquid towards the endcap initially. The endcap can be arranged to redirect the flow of contaminated liquid from an axial direction that is generally away from the filter assembly to an axial direction that is generally towards the filter assembly. The endcap can be arranged to redirect the flow of contaminated liquid in a manner that does not introduce significant turbulence. The endcap can be arranged to remove kinetic energy from the incoming contaminated liquid thereby reducing turbulence in the liquid. The endcap can be arranged to redirect the flow of contaminated liquid in a manner that does not introduce significant swirling to the contaminated liquid flow.

The internal profile of the endcap can have a tapered end wall or have a concave structure. The internal profile of the end cap can have a conical or frustoconical conical arrangement. An endcap having at least one of these arrangements does not introduce significant turbulence or swirling to the contaminated liquid flow. That is, the predominant direction of flow of the contaminated liquid after engaging the endcap is in an axial direction towards the filter assembly.

The filtration system can include an egress. The egress enables cleaned liquid to exit the vessel. The egress is preferably in fluid commination with the interior of the tubular filter. The egress can comprise an outlet pipe. The outlet pipe can be connected towards one end of the tubular filter, and preferably an upper end of the tubular filter. The outlet pipe can include a bend. For example, the outlet pipe can be arranged to redirect the flow of cleaned liquid from a substantially axial direction of the vessel to a substantially radial direction of the vessel. The outlet pipe can be arranged to redirect the flow of liquid through 90 degrees. The outlet pipe can pass through the side wall of the vessel.

The egress can be located above the impeller. This allows air to rise to the top of the filter and out of the egress. If the egress is located below the impeller air can become trapped in and around the impeller, which can prevent the impeller from functioning properly.

The filtration system can include a control system. The control system can comprise a Programable Logic Controller (PLC).

The filtration system can include a sensor. The control system can be arranged to receive signals from the sensor. The sensor can be a pressure sensor. For example, the pressure sensor can comprise a differential pressure switch or a differential pressure transducer.

The sensor can be arranged to determine how well the filter assembly is functioning, for example how well the cleaning system is functioning. The sensor can determine how clogged up the tubular filter is by solid contaminates.

The sensor can be arranged to detect a pressure difference between cleaned liquid on a filtered (interior) side of the filter and contaminated liquid on a non-filtered (exterior) side of the filter.

The filtration system can include a valve for removing solids from the vessel. The control system can be arranged to control operation of the valve for removing solids from the vessel. The valve can be located towards a lower end of the vessel. The control system can be arranged to automatically open the valve in response to signals received from the sensor. For example, when the output signal from the sensor reaches a first threshold value, such as a first threshold pressure value, the control system can be arranged to automatically open the valve to allow solids to flow out of the vessel. The control system can be arranged to automatically close the valve in order to minimise the loss of contaminated liquid from the vessel. For example, the control system can be arranged to close the valve after a predetermined time period, or the control system can be arranged to close the valve in response to signals received from the sensor. The control system can be arranged to count the number of times that the valve for removing solids from the vessel is opened and/or closed over a period of time. The frequency of opening and/or closing of the valve can be an indication that the mesh in the tubular filter is becoming increasingly blocked. Data collected by the control system can be displayed on a screen.

The filtration system can include an ingress valve for controlling the flow rate of contaminated liquid into the vessel via the ingress. The control system can be arranged to automatically control operation of the ingress valve at least partly in response to signals received from the sensor. The control system can be arranged to automatically close the valve, or to adjust the flow rate of contaminated liquid entering the vessel. For example, when the output signal from the sensor reaches a second threshold value, such as a second threshold pressure value, the control system can be arranged to automatically close the valve or to control the valve to adjust the flow rate of contaminated liquid into the vessel. The controller can reduce the flow rate of contaminated liquid into the vessel. Controlling the flow rate of contaminated liquid into the vessel helps the cleaning system to function so that the filter does not get to a condition where it can be so contaminated with solid waste that the cleaning system is no longer able to clean the filter. Controlling the flow rate of contaminated liquid into the vessel also reduces the frequency with which the valve for removing solids from the vessel has to operate. Furthermore, by controlling the flow rate into the vessel 5, it is possible to reduce the frequency with which it is necessary to manually clean or change the tubular filter. In some situations, the controller can increase the flow rate of contaminated liquid into the vessel.

The filtration system can include an egress valve for controlling the flow rate of cleaned liquid out of the vessel via the egress. The control system can be arranged to automatically control operation of the egress valve at least partly in response to signals received from the sensor. The control system can be arranged to automatically close the valve, or to control the valve to adjust the flow rate of cleaned liquid exiting the vessel. In some situations the controller can reduce the flow rate of cleaned liquid out of the vessel. In some situations, the controller can increase the flow rate of cleaned liquid out of the vessel.

The filtration system can include a receptacle arranged to receive solid waste from the valve for removing solids from the vessel. The receptacle can include a filter for capturing solids and a sump for collecting liquid. A pump can be provided for removing liquid from the receptacle. The liquid can be sent to a drain or back to the contaminated liquid source.

The filtration system can include a valve arranged to purge air from the vessel at start up. This valve can be located towards the endcap. This valve can be opened 10 when draining the vessel of liquid.

The filtration system can include a valve for draining liquid from the vessel. The valve can be located towards a lower end of the vessel.

The filtration system can include at least one restrictor located within the vessel. The restrictor can be arranged to reduce the cross-sectional area of the vessel. The restrictor can be located at a position approximately halfway along the length of the tubular filter. The restrictor can be, for example a plate. The plate can have a large central aperture. The tubular filter can sit within the aperture. The longitudinal axis of the tubular filter can be arranged coaxially with the axis of the aperture. A gap can be provided between an inner edge of the plate and the outer surface of the tubular filter. The purpose of the restrictor is to encourage solid contaminants to flow axially across the tubular filter. Since the vessel has a narrowed cross-sectional area at the location of the restrictor the contaminated liquid increases in velocity at that location. A lower pressure area is caused by the increased velocity as it passes through the restricted area thereby encouraging solids to move to a lower part of the tubular filter and then into the vessel sump.

The vessel can include a plurality of vessel sections. This provides ease of maintenance. The vessel can include a first axial section. The vessel can include a second axial section. The vessel can include a third axial section. The first axial section can be an upper section. The second axial section can be a mid-section. The third axial section can be a sump section.

The first axial section can be releasably connectable to the second axial section by a first coupling. The second axial section can be releasably connectable to the third axial section by a second coupling. The first and second couplings are preferably quick release couplings.

An example of an application of the invention relates to the filtration of river or pond water, or the like, where the principal intention is to produce a liquid from which particles above a given size have been removed. This can be, for example for use in agricultural or horticultural irrigation systems. In such applications the presence of relatively small amounts of suspended solids can lead to quite significant operational difficulties such as complete or partial blockage of one or more nozzles of the irrigation equipment. Another example of a context in which the invention has applicability is the removal of fibrous materials from liquids. For example, waste water from laundries can include fibres, such as lint, from fabrics that have been cleaned in washing machines. The filter system can be used to remove the fibres from the waste water, which enables the water to be recycled.

A further application of the invention includes the removal of the liquid portion from animal waste or human sewage.

Embodiments of the invention will now be described by way of example only with reference to the accompanying drawings in which: 23 Fig. 1 is a side view of a filter system in accordance with the invention; Fig. 2 is a cross-sectional view of the filter system of Fig. 1 along line A-A; Fig. 3 is a side view of part of the filter system of Fig. 1, which includes a rotor and a drive system arranged to drive the rotor; Fig. 4 is a cross-sectional view of Fig. 3; Fig. 5 is a diagrammatic layout of a control system and associated valves; Fig. 6 is a cross-sectional view of the filter system of Fig. 1 along line A-A, including diagrammatic indications of fluid and particulate movement within the filter assembly; Fig. 7 is a side view of an alternative rotor to that shown in Fig. 3, the alternative rotor can be used in the filter system of Fig. 1 in place of the rotor shown in Fig. 3, the rotor of Fig. 5 differing to the arrangement shown in Fig. 3 by the arrangement of outlets formed in the helical formations and the arrangement of a supporting core; Fig. 8 is a cross-sectional view of the rotor shown in Fig. 6; Fig. 9 is an isometric view of an alternative rotor to that shown in Fig. 3, the alternative rotor can be used in the filter system of Fig. 1 in place of the rotor shown in Fig. 3, the rotor of Fig. 8 differing to the arrangement shown in Fig. 3 by the arrangement of outlets formed in the helical formations and the arrangement of a supporting core; and Fig. 10 is a partially exploded view of the rotor of Fig. 8 to better show a rubber insert.

Figure 1 shows a filter system 1 in accordance with the invention. The filter system 1 includes a filter assembly 3 and a vessel 5 for housing at least part of the filter assembly 3.

The filter assembly 3 is arranged to filter at least some solid contaminates from a 5 contaminated liquid, such as contaminated water. The cleaned liquid is separated from the solids and can be directed to a downstream receptacle or process. The filter assembly 3 includes a tubular filter 7. Contaminated liquid is applied to an outer side 7A of the tubular filter 7. The liquid passes through the tubular filter 7 to the interior 7B of the tubular filter, leaving at least some of the solid contaminates on the 10 exterior side 7A of the tubular filter. Cleaned liquid is removed from the interior 7B of the tubular filter 7. Solid contaminates are removed from the outer side 7A of the tubular filter 7.

The tubular filter 7 can be made from any suitable material and has a suitable grade for removing at least some of the solid contaminates from the liquid. For example, the tubular filter 7 can comprise a mesh filter. The mesh filter can be made from a polymer such as nylon, and preferably a monofilament nylon, or polyester. The mesh filter can be made from a suitable metal, such as stainless steel. In some arrangements the metallic mesh can comprise first and second layers which are connected together. The first mesh layer can have a relatively fine mesh, for example of less than 500 microns, and the second layer, which is typically a backing layer, can have a coarser mesh. Apertures formed by the mesh typically have size (or grade), which is selected according to the liquid and solid contaminates being processed. A typical mesh aperture size for a contaminated water application is around 0.05-0.35mm The tubular filter 7 is closed at its upper end by an end plate 7C, save for an egress, which is described below. The tubular filter 7 is closed at its lower end by a drive system 29, which is described below.

The filter assembly 3 includes a cleaning system 9. The cleaning system 9 includes a rotor 11, which is located within the interior 7B of the tubular filter 7 (see Figures 2 and 3). The rotor 11 comprises first and second helical formations 13,15. The first and second helical formations 13,15 are intertwined with one another as can be seen in Figure 3. The first and second helical formations 13,15 are the same handed, that is have the same rotational direction. The first and second helical formations 13,15 are rotationally offset from one another. Preferably the first and second helical formations 13,15 are rotationally offset from one another by approximately 180 degrees, which gives a well-balanced rotor. The first helical formation 13 has a first internal conduit 17. The second helical formation 5 has a second internal conduit 19. Each conduit 17,19 preferably extends along substantially the full length of its respective helical formation 13,15. Thus the interior of each helical formation 13,15 is hollow. The first and second conduits 17,19 are each open at one end, which is typically a lower end of the rotor 11. Liquid can enter the first and second conduits 17,19 via the openings.

The first helical formation 13 includes at least one first outlet 21. The first outlet 21 is in fluid communication with first internal conduit 17. The first helical formation 13 can include a plurality of first outlets 21. Each first outlet 21 is in fluid communication with the first conduit 17 of the first helical formation 13. The or each first outlet 21 is preferably arranged in an outermost edge 23 of the first helical formation.

The second helical formation 15 includes at least one second outlet 25. The second 25 outlet 25 is in fluid communication with the second internal conduit 19. The second helical formation 15 can include a plurality of second outlets 25. Each second outlet is in fluid communication with the second internal conduit 19. The or each second outlet 25 is preferably located in an outer most edge 27 of the second helical formation.

Liquid entering the first and second internal conduits 17,19 via the open ends can exit the conduits 17,19 via their respective outlets 21,25.

Having the first and second outlets 21,25 located in outermost edges 23,27 of the helical formations 13,15 ensures that the outlets 21,25 are located close to an interior surface 7D of the tubular filter. Jets of liquid issuing from the outlets provide a strong cleaning effect due to the proximity of the jets to the inner surface 7D of the tubular filter. Each outlet 21,25 is preferably in the form of a through hole or slot. For example, each outlet can comprise a slot formed in the respective outermost edges 23,27 of the helical formations 13,15. The slots typically have a width of approximately 1mm. The length of each slot can be selected according to the desired cleaning function. For example, each helical formation 13,15 can have a single slot running along substantially the full length of the respective helical formation 13,15 (see Figure 3). Preferably width (or diameter) of the mesh apertures is smaller than the size of the outlets 21,25 width, or diameter. This helps to ensure that any solid contaminates that pass through the tubular filter 7 do not clog up the outlets 21,25. As a general rule of thumb, the size of each mesh aperture should be no more than 1/3 of the width, or diameter, of each outlet 21,25.

In use, a jet of liquid, typically liquid cleaned by the filter, exits each outlet 21,25 in a substantially radial direction to impinge upon the inner surface 7D of the tubular filter. As the rotor 11 rotates, the jets of liquid remove at least some of the solid materials lodged on the tubular filter 7. The solid materials are forced outward from the filter mesh back into the contaminated liquid on the exterior side 7A of the filter.

The axial length of each of the first and second helical formations 13,15 is approximately equal to the axial length of the tubular filter 7. This helps to ensure that substantially the full length of the tubular filter 7 is cleaned by the cleaning system 9. In preferred arrangements, the pitch of the helical formations 13,15 is approximately equal to the axial length of the tubular filter 7. That is, over the length of each helical formation 13,15, the helical formation 13,15 has approximately 1 turn.

The first and second helical formations 13,15 can be connected together along their lengths by a core 41, for example as shown in Figures 7 to 10, or at specific locations along their lengths, for example by a first connector 43A at a first (upper) end, a second connector 43B at a second (lower end), and by at least one third connector 43C at a location intermediate between the first and second ends (see Figure 3).

The rotor 11 has a complex structure because it includes internal conduits. The inventors have determined that the rotor 11 can be made by 3D printing or investment casting.

An advantage of the helical rotor 11 arrangement is that as the rotor 11 rotates it causes the solids in the contaminated liquid on the exterior side of the tubular filter 7 to move in an axially direction of the tubular filer 11, typically in a downwards axial direction, towards a collection area, such as a vessel sump, where the solids can be removed from the vessel 5. For at least some arrangements, the inventor has determined that, somewhat counter intuitively, the direction of the twist of the helix can be in the opposite direction to that expected to most effectively move the solids in the direction required.

The rotor 11 is supported at its upper end by the end plate 7C of the tubular filter. The rotor 11 is connected to the end plate 7C by a bearing 47, which enables the 25 rotor to rotate relative to the end plate 7C.

The cleaning system 9 includes a drive system 29 for rotating the rotor 11. The drive system 29 includes a pump 31 and a motor 33. The pump 31 includes an impeller 35 and a pump volute 37. The motor 33 is connected to the impeller 35 via a drive shaft 39. The motor 33 is arranged to drive the impeller 35 when the motor is activated in the direction of rotation shown in Figure 3. The pump volute 37 is mounted on a bearing 38. The pump volute 37 is fixedly connected to a lower end of the rotor 11, and the rotor 11 is locked for rotation with the pump volute 37. The impeller 35 is located within the pump volute 37, but is not locked for rotation with the pump volute 37. Instead, liquid provides a fluid coupling between the impeller 35 and the pump volute 37. The arrangement is such that as the motor rotates the impeller 35, liquid drag between the impeller 35 and pump volute 37 causes the pump volute 37 to rotate. However, the rotational speed of the pump volute 37, and hence rotor 11, is typically different from the rotational speed of the impeller 35. For example, in some embodiments, when at operating speed, the impeller 35 may have a rotational speed of around 2850 rpm whereas the pump volute 37 and the helical rotor 11 may rotate at approximately 120 rpm.

Thus, the rotor 11 is not driven directly by the motor 33 but rather is driven by the pump 31. An outlet 32 of the pump is in fluid connection with the openings of the internal conduits 17,19. The pump 31 drives cleaned liquid into the internal conduits 17,19 via the open ends of the conduits. As the rotor 11 rotates powerful jets of cleaned liquid from the interior 7B of the tubular filter issue from the outlets 21,25 and impinge upon the inner surface 7D of the tubular filter, thereby cleaning the filter as the rotor 11 rotates.

The drive shaft 39 is supported by the motor bearings. A sealing arrangement is 25 provided along the drive shaft 39 to prevent liquid from leaking out of the vessel 5. An upper and lower seals 46,48 are provided. An oil reservoir 52 is provided between the seals 46,48.

The vessel 5 can be elongate. For example, the vessel can comprise a pipe-like structure that is closed at a first end by an endcap 49, The vessel 5 can have a longitudinal axis, and the longitudinal axis can be arranged vertically. In this arrangement, the first end can be an upper end and the endcap 49 is located at the upper end. The second end is a lower end.

The vessel 5 can include a plurality of vessel sections. This provides ease of maintenance. The vessel 5 can include a first axial section 5A. The vessel 5 can include a second axial section 5B. The vessel 5 can include a third axial section Sc. The first axial section 5A can be an upper section. The second axial section 5B can be a mid-section. The third axial section 5C can be a sump section.

The first axial section 5A can be releasably connectable to the second axial section 5B by a first coupling 6. The second axial section 5B can be releasably connectable to the third axial section 5C by a second coupling 8. The first and second couplings 6,8 are preferably quick release couplings.

The filter system 1 includes an ingress for delivering liquid contaminated with solids into the vessel 5. The ingress comprises and input pipe 51. The input pipe 51 is oriented relative to the vessel 5 such that incoming contaminated liquid is directed towards the endcap 49. Preferably the input pipe 51 is arranged such that incoming contaminated liquid flows into the vessel 5 in an axial direction, and preferably an upwardly axial direction. For example, the input pipe 51 can enter the vessel 5 through a sidewall 53 and can include a bend 55 which redirects the flow of contaminated liquid from a generally radial direction to a generally axial direction.

The input pipe 51 delivers contaminated liquid into the vessel at a position that is intermediate between the endcap 49 and the tubular filter 7. When the longitudinal 25 axis of the vessel 5 has a generally vertical orientation, the endcap 49 is located above the input pipe, and the input pipe is located above the tubular filter 7. Thus contaminated fluid coming into the vessel 5 initially flows upwards towards the endcap 49. The endcap 49 has a conical, frustoconical or concave inner profile 50. The conical or concave inner profile 50 of the endcap 49 redirects the contaminated liquid from an axial flow generally away from the tubular filter 7 to an axial flow generally towards the tubular filter 7. That is, axially flow in a generally downwardly direction, which is assisted by gravity. The shape of the endcap 49 is designed to minimise the amount of turbulence and swirling flow within the contaminated liquid as it changes direction. Having an endcap 49 with a conical or concave inner profile 50 produces a relatively non-turbulent axial flow toward the tubular filter 7.

The vessel 5 includes a restrictor 57. The restrictor 57 narrows the cross-sectional area of the vessel 5 at a location that is approximately half-way down the length of the tubular filter 7. For example, the restrictor 57 can comprise a plate extending transversely across the vessel 5, the plate having a central aperture that is slightly larger than the external diameter of the tubular filter 7. The gap between an inner edge of the restrictor 57 and an external surface of the tubular filter enables the contaminated liquid to flow over the external surface of the tubular filter. The purpose of the restrictor 57 is to encourage solids to move axially across the filter mesh. The restrictor 57 also has the effect that backwashed solids tend to move to the lower half of the filter. A lower pressure area is caused by the increase velocity of the fluid as it passes through the restricted area thereby encouraging solids to move to the lower half of the tubular filter 7 and then into the solids collection chamber.

The filter system 1 preferably includes an ingress valve 59 for controlling flow of contaminated liquid into the vessel 5 via the ingress. The valve 59 can be a 25 proportional valve.

The filter system 1 includes an egress for allowing cleaned liquid to exit the vessel 5. The egress can comprise an outlet pipe 61. The outlet pipe 61 is in fluid communication with the interior 7B of the tubular filter and is arranged to direct cleaned water to a downstream receptacle or process. The outlet pipe 61 is supported by the end plate 7C and exits the vessel 5 through the sidewall 53. The filter system 1 can include an egress valve 63 for controlling flow of contaminated liquid out the vessel 5 via the egress in addition, or as an alternative, to the ingress valve 59. The egress valve 63 can be a proportional valve.

The filter system 1 includes a valve 65 for removing solids from the vessel. The valve 65 can be opened to remove solids located in the collection part of the vessel, such as a sump 67. The valve 65 is preferably a fast-acting valve so that it can be opened and closed quickly, preferably in a time of less than 3 seconds. The reason for the requirement for speed is as that as the amount of solids trapped on the filter mesh accumulates there will come a time when the concentration of solids, for a given flow rate through the filter, around the filter is too high for the cleaning system 9 to keep the filter clear. To minimise the amount of fluid lost when these solids are removed, it is important that when the filter cleaning system is close to being overcome by the solids concentration around the filter that the valve 65 opens quickly. If the valve 65 opens too slowly there is a risk that the tubular filter 11 will block before the valve 65 opens.

A valve 69 can be located adjacent the endcap 49. The valve 69 can be used when priming the system to allow air to escape. For example, the valve 69 can be opened to allow air to escape. It can also be used when draining the vessel 5. The valve 69 is typically closed during normal operation.

A valve 71 can be located adjacent the sump 67. The valve 71 can be used to drain liquid from the vessel 5, for example for maintenance purposes. The valve 71 is typically closed during normal operation.

The filter system 1 can include a control system 73 (see Figure 5), for example in the 5 form of a Programable Logic Controller (PLC). The filter system 1 can include a sensor 75. The sensor 75 is used to provide an indication how well the filter assembly is performing, for example if the cleaning system 9 is functioning properly. The sensor 75 is connected to the control system 73, and the control system 73 is arranged to receive signals from the sensor 75. At least one, and preferably each, of the valves 10 59, 63 and 65 includes an actuator that is controllable by the control system 73. The control system 73 is preferably arranged to automatically control operation of at least one of the valves 59, 63 and 65. The control system 73 can be arranged to automatically control operation of at least one, and preferably each, of the valves 59, 63 and 65 at least partly in response to signals received from the sensor 75.

The sensor 75 is preferably a pressure sensor. The sensor 75 can be arranged to measure differential pressure. The sensor 75 has a first conduit 77 connected to the vessel on the unfiltered side 7A and a second conduit 79 attached to the vessel on the filtered side 7B. Typically, in normal operation the unfiltered side 7A has a higher pressure than the filtered side 7B. The inventor has determined that a differential pressure transducer in the 0-200mb range is suitable for contaminated water applications. Alternatively, a differential pressure switch can be used.

The control system 73 can detect the pressure differential between the unfiltered 7A and filtered sides 7B of the tubular filter 7. The inventor has determined that when the pressure differential reaches a first threshold value, typically around 40 mb for a contaminated water application, that is an effective time to automatically actuate the valve 65 in order to remove solid contaminates from the sump 67. The control system 73 is arranged to automatically close the valve 65 when the pressure differential detected by the sensor 75 falls to a second threshold value. The solids removed from the vessel 5 are routed to a receptacle (not shown), which can include a filter for separating the solids from any liquid that was removed with the solids.

The liquid can be pumped away to a drain or back to the contaminated liquid source.

The control system 73 can be programmed to close at least one of the ingress valve 59 and the egress valve 63 if the pressure differential detected by the sensor 75 reaches a second threshold value. The second threshold value indicates that the tubular filter 7 has become blocked and that the cleaning system 9 is unable to unblock the filter. For example, for a contaminated water application, the second threshold value can be around 120mb. The control system can include an indicator, and preferably a visual indicator such as a warning light. When the control system 73 determines that the second threshold value has been reached it actuates the indicator, for example it illuminates the warning light. At this stage, it is necessary to drain off the liquid from the vessel 5 by opening valve 71 and manually cleaning or replacing the tubular filter 7.

The control system 73 can also be programmed to control operation of the ingress valve 59 in order to control the flow rate of contaminated liquid into the vessel 5. The control system 73 can be programmed to increase the flow of contaminated liquid into the vessel if the control system 73 determines from the signals received from the senor 75 that the pressure difference is relatively low. This helps to ensure that there is a steady flow of contaminated liquid into the vessel 5. The control system 73 can be programmed to decrease the flow of contaminated liquid into the vessel if the control system 73 determines from the signals received from the senor 75 that the pressure difference is relatively high. This helps to ensure that the filter 7 does not become clogged by solid contaminants by controlling the rate at which contaminates flow into the vessel 5. Suitable control of the ingress valve 59 balances liquid throughput while maintaining operation of the filter assembly 3.

The control system 73 can also be programmed to control operation of the egress valve 61. This controls the flow rate of cleaned liquid out of the vessel 5. Appropriate 5 control of the egress valve 61 affects the throughput of liquid the system 1, and can help to prevent the tubular filter 7 from clogging up.

Figures 7 and 8 show a first alternative rotor 111. The first alternative rotor 111 can be used in the filter system of Figure 1 in place of the rotor 11 shown in Figure 3. The first alternative rotor 111 of Figures 7 and 8 differs from the arrangement shown in Figure 3 by the arrangement of outlets 121 formed in the helical formations 113,115 and the arrangement of a supporting core 143.

Several slots 121 are distributed along the length of each respective helical formation 113,115. Each slot 121 has a relatively short length (see Figure 7). It is clear from Figure 7 that each slot is formed through the thickness of the respective helical formation 113,115 and is in fluid communication with their respective internal conduits 117,119.

In another alternative rotor (not shown), there is provided a small number of relatively long slots running along substantially the full length of each respective helical formation.

Figures 9 and 10 show a second alternative rotor 211. The second alternative rotor 211 can be used in the filter system of Figure 1 in place of the rotor 11 shown in Figure 3. The rotor 211 of Figures 9 and 10 differs from the arrangement shown in Figure 3 by the arrangement of first and second outlets 221,225 formed in the respective helical formations 213,215 and the arrangement of a supporting core 243.

The supporting core 243 runs along substantially the full length of the first and second helical formations 213,215.

At least some of the first and second slots 221,225 are formed in resilient bodies 280, which are mounted in large apertures 282 formed in the first and second helical formations 213,215. For example, the resilient bodies 280 can be made from rubber or a rubber-like substance. The outlets 221,225 are in the form of several relatively short slots 221,225.

The apertures of the tubular filter in this embodiment can be larger than the width of the outlets 221,225 formed in the resilient bodies 280, since the resilient bodies 280 can flex under pressure which enables the outlets 221,225 to increase in size (i.e. can open further) under pressure thereby allowing larger particles to pass through the outlets 221,225. In some arrangements, having the first and second outlets 221,225 formed in resilient bodies 280 enables the filter apertures to be greater than 0.5mm in width, for example the slot width can be in the range 0.5mm to 5mm.

In some arrangements, each of the first and second slots 221,225 is formed in a respective resilient body 280.

It will be appreciated that the embodiments described above are examples of the invention only and should not be considered as limiting the scope of the claims. Furthermore, any feature of any embodiment can be combined with any other embodiment described herein to form a new embodiment. Modifications can be made to the above embodiments that fall within the scope of the claims, for example the rotor can have a different number of helical formations. The rotor can include a single helical formation. The rotor can include at least one further helical formation. Thus, the rotor comprises at least one helical formation, and can comprise a plurality of helical formations.

Other materials can be used for the filter mesh. Any suitable material can be used.

Each outlet formed in the helical formations can comprise a respective nozzle.

The or each first outlet can be arranged in another part of the first helical formation, for example in a helical surface thereof The or each second outlet can be arranged 5 in another part of the second helical formation, for example in a helical surface thereof.

The pitch of the helical formations can be different from that indicated above.

The control system can be arranged to control operation of at least one of: valve 69 and valve 71.

Claims

CLAIMS1. A filter assembly for filtering liquids contaminated with solid material, the filter assembly including: a tubular filter; and a cleaning system for cleaning the tubular filter, the cleaning system including a rotor mounted within the tubular filter, the rotor having a first helical formation, the first helical formation including a first conduit and at least one first outlet in fluid communication with the first conduit, wherein the first conduit is arranged to provide liquid to the first outlet, and the first outlet is arranged to direct jets of liquid on to an internal surface of the tubular filter.
2. The filter assembly of claim 1, wherein the rotor includes a second helical formation.
3. The filter assembly of claim 2, wherein the second helical formation includes a second conduit and at least one second outlet, wherein the second conduit is arranged to provide liquid to the second outlet, and the second outlet is arranged to direct jets of liquid on to the internal surface of the tubular filter.
4. The filter assembly of any one of the preceding claims, including drive means for rotating the rotor.
5. The filter assembly of claim 4, wherein the drive means includes a motor.
6. The filter assembly of claim 4 or 5, wherein the drive means includes a pump.
7. The filter assembly of claim 6 when dependent on claim 4, wherein the pump includes an impeller and a pump volute, the pump volute is connected to the rotor and the impeller is connected to the motor, wherein operation of the motor causes the impeller to rotate and liquid within pump causes the pump volute and the rotor to rotate.
8. The filter assembly of claim 6 or 7, wherein the pump is arranged to supply liquid to the conduit(s).
9. The filter assembly of any one of the preceding claims, wherein the tubular filter comprises a tubular metallic mesh filter.
10 The filter assembly of any one of the preceding claims, wherein the tubular filter comprises a tubular polymer mesh filter.
11. The filter assembly of any one of the preceding claims, wherein the tubular filter includes a mesh having apertures that are less than or equal to 0.5mm in diameter.
12 The filter assembly of any one of the preceding claims, wherein the tubular filter includes a mesh having apertures, wherein the widths of the rotor outlets are at least twice, and preferably at least three times, the size of the mesh apertures.
13. The filter assembly of any one of the preceding claims, wherein the length of the tubular filter is greater than the diameter of tubular filter.
14. The filter assembly of any of the preceding claims, wherein the or each helical formation is manufactured in one piece, for example by 3D printing or investment casting.
15. The filter assembly of any of the preceding claims, wherein at least one of the first outlets is formed in a first resilient body, and the first resilient body is inserted into a first aperture formed in the first helical formation.
16.A filtration system, including: a filter assembly according to any one of the preceding claims, and a vessel arranged to house at least part of the filter assembly.
17. The filtration system according to claim 16, wherein the vessel includes an ingress having an opening facing in an axial direction, the ingress is arranged to supply liquid contaminated with solids into the interior of the vessel in an axial direction of the vessel.
18. The filtration system according to claim 17, wherein the opening faces away from the filter assembly, the arrangement being such that contaminated liquid entering the vessel is initially directed in an axial direction away from the filter assembly.
19. The filtration system of any one of claims 16 to 18, wherein the vessel includes an endcap, the ingress directs the flow of contaminated liquid axially towards the endcap, and the endcap redirects the flow of contaminated liquid axially towards the filter assembly.
20. The filtration system of claim 19, wherein an inner profile of the endcap has at least one of a tapered side wall, a concave structure, a conical structure or a frustoconical structure.
21 The filtration system of any one of claims 16 to 20, including an egress enabling cleaned liquid to exit the vessel, wherein the egress is in fluid commination with the interior of the tubular filter.
22. The filtration system of claim 21 when dependent on claim 7, wherein the egress is located above the impeller.
23. The filtration system of any one of claims 16 to 22, including a control system.
24. The filtration system according to claim 23, including a sensor, wherein the control system is arranged to receive signals from the sensor.
25. The filtration system according to claim 24, wherein the sensor is arranged to detect if the cleaning system is operating satisfactorily.
26. The filtration system according to claim 24 or 25, wherein the sensor is arranged to detect a pressure difference between cleaned liquid on a filtered side of the filter and contaminated liquid on a non-filtered side of the filter.
27. The filtration system of any one of claims 16 to 26 when dependent on claim 23, including a valve for removing solids from the vessel, wherein the control system is arranged to control operation of the valve for removing solids from the vessel at least partly in response to signals received from the sensor.
28. The filtration system of any one of claims 16 to 27 when dependent on claim 23, including an ingress valve for controlling the flow rate of contaminated liquid into the vessel via the ingress, wherein the control system is arranged to control operation of the ingress valve at least partly in response to signals received from the sensor.
29. The filtration system of any one of claims 16 to 28 when dependent on claim 23, including an egress valve for controlling the flow rate of cleaned liquid out of the vessel via the egress, wherein the control system is arranged to control operation of the egress valve at least partly in response to signals received from the sensor.
30. The filtration system of any one of claims 16 to 29, including a valve arranged to purge air from the vessel at start up.
31. The filtration system of any one of claims 16 to 30, including a valve for draining liquid from the vessel.
32. The filtration system of any one of claims 16 to 31, including at least one restrictor located within the vessel, the restrictor being arranged to change the flow characteristics of the contaminated liquid.
33. The filtration system of any one of claims 16 to 32, wherein the vessel includes a plurality of vessel sections.
34. The filtration system of claim 33, including a first axial section, a second axial section and a third axial section.
35. The filtration system according to claim 34, wherein the first axial section is releasably connectable to the second axial section by a first coupling; and/or the second axial section is releasably connectable to the third axial section by a second coupling.